WASHINGTON -- Rep. Ed Markey on Friday denounced California billionaire Tom Steyer's involvement in the Massachusetts Senate special election. The hedge fund manager turned environmentalist has threatened to spend big money if Markey's opponent, Rep. Steve Lynch, does not renounce his support for the controversial Keystone XL oil pipeline. Now Markey is saying thanks but no thanks for the support.

"As I stated when I first learned about Tom Steyer's demands on Monday, these kinds of tactics have no place in our political discourse and should be repudiated," said Markey in a statement. "Mr. Steyer should immediately withdraw his threats and ultimatum, and stay out of this Senate race. This campaign should be about the people of this state, and I remain committed to giving Massachusetts voters a debate about the issues they care about most"

Steyer has been working with several young Massachusetts advocates on a campaign against the pipeline, which would stretch 1,700 miles from Canada to oil refineries in Texas. In a public letter on Monday, the environmentalists asked Lynch to do one of two things: "Either act like a real Democrat and oppose Keystone's dirty energy. Or, get a sworn, binding statement -- with securities law enforcement -- from TransCanada and the refiners that all of the Keystone-shipped oil will stay here [in the U.S.]." Otherwise, Steyer said he'd launch an education campaign against Lynch.

While Markey, having previously called on primary candidates on both sides of the aisle to reject money from outside interest groups, has already has distanced himself from Steyer before, his statement on Friday is his most definitive rejection to date.

Chris Lehane, a spokesman for Steyer, told HuffPost in an email, "While we have have great respect for Ed Markey and know he is a real Democrat, the issue in this race is whether Steve Lynch is running to be the senator from Canada fighting for increasing the wealth of a foreign oil company or a senator from Massachusetts who will stand for the common good of the Commonwealth."

Frank Callahan, president of the Massachusetts Building Trades Council is similarly displeased with Steyer's involvement. "I guess I shouldn't have been surprised by the arrogance of another out-of-state and out-of-touch billionaire who identifies himself as a 'clean energy philanthropist' when he interjected himself into our U.S. Senate race with a threatening letter to Congressman Stephen Lynch," Callahan said. "As a lifelong resident of Massachusetts, I've had enough of Washington insiders and outside environmental groups attempting to dictate who we can have for our elected representatives. I and my fellow residents of Massachusetts are perfectly capable of deciding who will represent us in the United States Senate. Keep your money -- our votes are not for sale."

The union leader's ire was puzzling to Craig Altemose, one of the environmental activists on the letter, who says the pipeline's job estimates, which have been widely reported as overblown, will not do anything to help people in the state of Massachusetts.

"Local unions in [Massachusetts] will not see a single job for the KXL pipeline, however temporary," he told HuffPost in an email. "And the pipeline -- and the climate change it will accelerate -- will do permanent damage to the Commonwealth ... If Lynch wants to support local union jobs in Massachusetts, he should look no further than Cape Wind, which will create hundreds of temporary construction jobs here in the Commonwealth and more permanent jobs than the entire 1,700 mile pipeline."

Last year Steyer spent many millions of dollars on Proposition 39, California ballot initiative that funnels money into clean energy projects by closing a tax loophole.